Homogenization is the breaking down and mixing of the components of an emulsion or dispersion. A major use of homogenizers is to break down and disperse milk fat into the bulk of skim milk. This delays creaming of milk fat globules. Homogenizers are also used to process other emulsions such as silicon oil and to process dispersions such as pigments, antacids and various paper coatings.
In the most widely used type of homogenizer, the emulsion is introduced at high pressure of 500 psi to 10,000 psi to a central bore within an annular valve seat. The emulsion is forced out through a narrow gap between the valve seat and a valve member. Through the gap, the emulsion undergoes extremely rapid acceleration as well as an extreme drop in pressure. This violent action through the valve breaks down globules within the emulsion to produce the homogenized product.
The degree of homogenization is a function of the difference between the pressure of the emulsion at the inlet of the valve and the pressure at the outlet. In the past, homogenizers have not typically been required to operate at inlet pressures of greater than 10,000 psi. However, recent applications such as cell disruption have required significantly higher inlet pressures of about 15,000 psi or more.
A typical homogenizer system includes a homogenizer valve mounted to the side of a pump block. The pump is a plunger pump having multiple plungers which draw from a common suction manifold and discharge into a common discharge manifold delivering high pressure fluid to the homogenizer valve. For a constant flow rate provided by the pump, a desired homogenizing pressure is maintained by adjusting the gap between the valve member and the valve seat. In conventional systems, that adjustment is made by an actuator assembly. One type of actuator assembly is a spring-loaded handwheel which requires manual manipulation to adjust the homogenizing pressure. Another type of actuator assembly is a hydraulic or pneumatic valve actuator system. The hydraulic or pneumatic system provides for regulation of process pressure via a valve on a control panel, eliminating the need for manual handwheel adjustments.